Downlink control channel in wireless systems

ABSTRACT

Systems, methods, and instrumentalities may be disclosed for implementing a flexible radio access communication system. A flexible radio access communication system may be supported using spectrum of varying size, including aggregation of non-adjacent carriers in the same and/or in different frequency bands. A wireless transmit/receive unit (WTRU) may receive a first transmission via a common downlink control channel. The first transmission may include first control information. The first control information may include information regarding the configuration of a first dedicated downlink control channel of one or more dedicated control channels. The WTRU may receive a second transmission via the first dedicated downlink control channel of the dedicated control channels. The second transmission may include second control information. The second control information may be associated with a transmission of a first transmission type. The dedicated downlink control channels may be used for providing control information associated with different types of transmissions.

CROSS REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/209,797 filed on Aug. 25, 2015, which is incorporated herein byreference as if fully set forth.

BACKGROUND

Orthogonal frequency division multiplexing (OFDM) may be a signal formatused for data transmissions in long term evolution (LTE) and IEEE 802.11communication systems. OFDM may divide a spectrum into multiple parallelorthogonal subbands. A subcarrier may be shaped using a rectangularwindow in the time domain leading to sinc-shaped subcarriers in thefrequency domain. OFDMA may benefit from frequency synchronization andtight management of uplink timing alignment within the duration of thecyclic prefix to maintain orthogonality between signals and to reduceinter-carrier interference. Such synchronization may not be well-suitedin a system in which a wireless transmit/receive unit (WTRU) isconnected to multiple access points simultaneously. Additional powerreduction may be applied to uplink transmissions for compliance withspectral emission guidelines to adjacent bands, e.g., in the presence ofaggregation of fragmented spectrum for the WTRU's transmissions.

SUMMARY

A wireless communication system may enable flexible spectrum usage,deployment strategies, and operation. A wireless/transmit receive unit(WTRU) and/or one or more base station devices/access points may beconfigured to utilize spectrum of varying size, for example includingaggregation of non-adjacent carriers in the same and/or in differentfrequency bands (e.g., licensed or unlicensed), in order to implement aflexible radio access communication system. The WTRU and/or base stationdevice may utilize one or more of narrowband and wideband transmissionsin order to implement a flexible radio access communication system. AWTRU and/or base station device may utilize one or more (e.g.,different) duplexing methods in order to implement a flexible radioaccess communication system. For time-division duplexing (TDD), the WTRUand/or base station device may utilize dynamically variable DL/ULallocation in order to implement a flexible radio access communicationsystem. The WTRU and/or base station device may utilize variable TTIlengths in order to implement a flexible radio access communicationsystem. The WTRU and/or base station device may utilize scheduled andunscheduled transmissions in order to implement a flexible radio accesscommunication system. The WTRU and/or base station device may utilizesynchronous and asynchronous transmissions in order to implement aflexible radio access communication system. The user plane may beseparated from the control plane. The WTRU and/or base station devicemay utilize multi-node connectivity in order to implement a flexibleradio access communication system.

A WTRU and/or base station device may utilize resource elements in orderto implement a flexible radio access communication system. Differenttypes of resource elements may be defined, determined, and/or used. Forexample, resource elements (REs) may be defined, determined, and/orused. Different types of REs may be defined, determined, and/or used fordifferent types of transmissions. Different types of REs may be defined,determined, and/or used based on one or more of a frequency space and/ora time length. A resource block (RB) may be defined, determined, and/orused. For example, an RB may comprise one or more resource elements. Oneor more (e.g., different) types of RBs may be defined, determined,and/or used, for example, for different types of transmissions. Forexample, one or more RB may be defined, determined, and/or used,depending on which types of one or more REs are comprised within the RB.Information relating to the determined RB type may be sent to a wirelesstransmit/receive unit (WTRU). For example, a WTRU may receiveinformation relating to the determined RB type from a base state device.

A WTRU and/or base station device may utilize flexible physical resourcedefinition information in order to implement a flexible radio accesscommunication system. For example, a WTRU may receive flexible physicalresource definition information from a base station device. A WTRU mayreceive RE and/or RB definitions (e.g. RE and/or RB definitions withflexible structure) from a base state device. A WTRU may receive controlchannel resource unit definition information. For example, a WTRU mayreceive control resource element (CRE) and/or control resource elementgroup (CREG) definition information in order to configure and/orimplement a flexible radio access communication system. By usingflexible resource definitions (e.g., CREs, CREGs, etc.), the WTRU may beconfigured to dynamically and/or semi-statically utilize differentresource types, for example for different types of transmissions and/ortransmission for different purposes/appellations/use cases. Differenttypes of transmissions, such as using different waveform types and/ordifferent RF processing chains, may be used depending on the resourcetype.

A WTRU and/or base station device may utilize control channel resourceconfiguration information in order to implement a flexible radio accesscommunication system. For example, a WTRU may receive control channelresource configuration information from a base station device. Thecontrol channel resource configuration information may be based on aservice type. For example, control channel resource configurationinformation may be based on a hierarchical control channel structure, aflexible control resource configuration, and/or a search spaceconfiguration. The search space configuration may be provided accordingto a service type and/or collision handling when two or more searchspaces are used.

A WTRU and/or base station device may utilize control information inorder to configure and/or implement a flexible radio accesscommunication system. For example, a WTRU may receive cyclic redundancycheck (CRC) attachment information from a base station device, based onservice type and/or based on a payload size. The WTRU may receive startand/or stop indications (e.g., for repetitive transmission), forexample, from a base station device.

A WTRU and/or base station device may utilize WTRU reportinginformation. For example, a WTRU and/or base station device may utilizeWTRU reporting information in order to configure and/or implement aflexible radio access communication system. For example, a WTRU and/orbase station device may utilize WTRU reporting information for linkadaptation of the control channel. A WTRU and/or base station device mayutilize control channel processing time reporting information in orderto configure and/or implement a flexible radio access communicationsystem. The WTRU and/or base station device may utilize a preferredsearch space and/or CC candidate reporting information in order toconfigure and/or implement a flexible radio access communication system.

A WTRU and/or a base station devices may use a transmission scheme inorder to implement a flexible radio access communication system. Forexample, a WTRU and/or a base station device may use a CP-based OFDMtransmission scheme that may employ a downlink physical layer. Thedownlink physical layer may be modified in pilot signal density and/orlocation. The WTRU and/or a base station device may use a downlinktransmission scheme that may be based on a multicarrier waveform.

A WTRU and/or a base station device may use spectrum flexibility.Spectrum flexibility may enable the WTRU and/or the base station deviceto be deployed in different frequency bands with differentcharacteristics. For example, a high degree of spectrum flexibility mayenable deployment in different frequency bands with different duplexarrangements. A WTRU and/or a base station device may achieve bandwidthflexibility in a flexible radio access wireless communication system.Bandwidth flexibility may be achieved because RF requirements for anoperating bandwidth (e.g., a given maximum operating bandwidth) in aband may be met without the introduction of additional allowed channelbandwidths for that operating band.

A WTRU and/or a base station device may utilize flexible deploymentstrategies, and/or flexible operations. Flexible deployment strategiesand/or flexible operations may include flexible spectrum allocation.Flexible deployment strategies and/or flexible operations may enabledeployment in different and/or variable sizes of available spectrum,including contiguous and non-contiguous spectrum allocations in the sameor different bands. A WTRU and/or a base station device may supportnarrowband and/or wideband. A WTRU and/or a base station device maysupport one or more (e.g., different) duplexing methods.

A WTRU and/or a base station device may organize downlink and/or uplinktransmissions into radio frames. The radio frames may be characterizedby one or more fixed aspects (e.g., location of downlink controlinformation) and/or one or more varying aspects (e.g., transmissiontiming, supported types of transmissions). A basic time interval (BTI)may be expressed in terms of an integer number of one or more symbols. Asymbol duration may be a function of the subcarrier spacing applicableto the time-frequency resource. For FDD, subcarrier spacing may differbetween the uplink carrier frequency f_(UL) and the downlink carrierfrequency f_(DL) for a given frame. A transmission time interval (TTI)may be the minimum time supported by the system between transmissions(e.g., consecutive transmissions).

A WTRU and/or a base station device may support a scheduling function inthe MAC layer. Scheduling modes that may be supported may includenetwork-based scheduling and/or WTRU-based scheduling. For network-basedscheduling and/or WTRU-based scheduling, scheduling information may bevalid for one or more TTIs. Network-based scheduling may enable thenetwork to manage radio resources (e.g., the available radio resourcesassigned to different WTRUs). For example, network-based scheduling mayenable the network to manage available radio resources assigned todifferent WTRUs to optimize the sharing of such resources. WTRU-basedscheduling may enable the WTRU to access (e.g., opportunisticallyaccess) uplink resources with minimal latency on a per-need basis.WTRU-based scheduling may enable the WTRU to access uplink resourceswithin a set of shared and/or dedicated uplink resources (e.g.,dynamically or fixed uplink resources) assigned by the network.

A WTRU and/or a base station device may use a resource element (RE) as aresource unit (e.g., a minimum resource unit) in a physical resourcegrid. One or more of REs may be defined in a physical resource grid. AnRE may include one or more of the following: a subcarrier of amulti-carrier waveform in a time symbol, a time symbol, a sequence of amodulated symbol in which multiple sequences may be used to carry datasymbols, and/or a resource unit that may carry a data symbol.

A WTRU and/or a base station device may use one or more downlink controlchannels (and/or downlink control channel types). For example, one ormore downlink control channels (and/or downlink control channel types)may be used based on one or more of a traffic type for a data channel,an information type carried in the control channel, a reference signal,RB types used for the downlink control channel transmission, SOM, and/orWTRU types (or categories) that may receive or monitor the controlchannel. A downlink control channel may be interchangeably used as adownlink control channel type, control channel, and control channeltype.

A WTRU and/or a base station device may use a downlink control channelbased on a traffic type of the data channel scheduled by the downlinkcontrol channel. A first type of downlink control channel may be usedfor a first traffic type, and a second type of downlink control channelmay be used for a second traffic type. The traffic type may be a datatraffic that may use a low latency connection. The traffic type may be adata traffic that may use a narrowband transmission. The traffic typemay be a data traffic that may use a transmission with a highreliability. The traffic type may be a control traffic that may carrybroadcast or multicast information. The traffic type may be a controland/or data traffic that may be transmitted and/or received betweenWTRUs.

A WTRU and/or a base station device may use a downlink control channelbased on a WTRU capability. A first downlink control channel type may beused for a WTRU with a limited WTRU capability. A second downlinkcontrol channel type may be used for a WTRU with a full WTRU capability.The WTRU capability may include a supportable bandwidth, a number ofreceive antennas, a number of transmit antennas, a receiver beamformingcapability, and/or a multiple antenna receiver type. A downlink controlchannel may be defined, determined, and/or or used based on a referencesignal. For example, a first downlink control channel may be associatedwith a first type of reference signal, and/or a second downlink controlchannel may be associated with a second type of reference signal (e.g.,WTRU-specific).

A WTRU and/or a base station device may define a control resourceelement (CRE) with a group of one or more REs. The CRE may be usedinterchangeably with resource element group (REG) and enhanced REG(EREG). A CRE may be defined and/or determined with a fixed number ofREs. The available RE for a CRE may be referred to as an RE, which maybe used for the control channel. The configuration of a higher prioritysignal may be known to a WTRU.

A CRE may be defined with a variable number of REs. For example, thenumber of REs per CRE may be determined based on an RE type for the REsin the associated CRE. A CRE that may include a first type of REs may bedefined with a first number of REs. A CRE that may include a second typeof REs may be defined with a second number of REs. The number of REs perCRE may be determined based on an RB type (e.g., based on an RB type ofan RB in which the CRE may be located). A CRE in a first type of RB maybe defined with a first number of REs. A CRE in a second type of RB maybe defined with a second number of REs. One or more CREs may be definedfor a time cycle. The number of REs per CRE may be determined based on anumber of available REs within an RB.

A WTRU and/or a base station device may use one or more CRE types. TheCRE type may be determined based on a control channel type and/based onan RE type. A CRE type for a first control channel may be defined and/orconfigured with REs located in the same time symbol. A CRE type for asecond control channel may be defined and/or configured with REs locatedin the same subcarrier. The CRE type may be determined based on an RBtype (e.g., based on an RB type of the configured RBs for the controlchannel). One or more RBs may be configured for a control channel. TheCRE type may be determined based on an RE type of REs that may begrouped to form a CRE. For example, if a CRE is defined or configuredwith REs that may be a defined RE type, the CRE type may be determinedbased on the RE type of the REs associated with the CRE. The CRE typemay be determined based on a configuration, a WTRU capability and/orcategory, a traffic type, a CP length used for a waveform, and/or asubframe type.

A WTRU and/or a base station device may define and/or configure acontrol resource element group (CREG). For example, a control resourceelement group (CREG) may be defined and/or configured with a group ofone or more CREs. A CREG may be used interchangeably with controlchannel element (CCE) and/or enhanced CCE (ECCE). CREs with a same typemay be grouped to form a CREG. A CREG type may be determined based onthe CRE type. CREs may be grouped to form a CREG.

A WTRU and/or a base station device may define and/or use one or moreCREG types. The CREG type for a downlink control information (DCI)transmission and/or a downlink control channel may be determined basedon a channel type (e.g., the associated channel type). A WTRU and/or abase station device may use a reference signal to demodulate a CREand/or a CREG. One or more reference signal structures may be used for adownlink control channel. A first reference signal structure may be acell-specific reference signal. A cell-specific reference signal may beused for one or more downlink channels. A second reference signalstructure may be a dedicated reference signal. A dedicated referencesignal may be used for a specific downlink channel. A dedicatedreference signal may be used for a data channel. A dedicated referencesignal may be transmitted in a localized resource. A dedicated referencesignal may be located within a resource that may be allocated, received,and/or decoded by a WTRU.

A WTRU and/or a base station device may use a hierarchical downlinkcontrol channel structure. A common downlink control channel and/or oneor more dedicated downlink control channel may be used. The common DLcontrol channel may be transmitted to and/or received by one or moreWTRUs, regardless of service type, traffic type, transmission type, WTRUcategory, and/or WTRU capabilities. The dedicated DL control channel maybe transmitted to and/or received by a WTRU with a defined service type,traffic type, transmission type, WTRU category, and/or WTRU capability.

A nominal system bandwidth may be defined with a subset of a totalsystem bandwidth. A frequency band other than the nominal systembandwidth may be used based on configurations indicated or received fromthe nominal system bandwidth. A common DL control channel may betransmitted from a base station device (e.g., eNB) and/or received by aWTRU in a nominal system bandwidth. A dedicated DL control channel maybe configured in a frequency band within a total system bandwidth. Forexample, a dedicated DL control channel for a control channel type maybe located in a frequency band used and/or configured for the traffictype associated with the control channel type. A dedicated DL controlchannel for a traffic type may be located in the frequency band assignedand/or used for the traffic type. One or more dedicated DL controlchannels may be located in a different frequency band that may beassociated with the traffic type. A time/frequency location of adedicated DL control channel may be predefined within a frequency bandthat may be configured for a traffic type and/or a service type.

A nominal system bandwidth may be located in a different frequencyregion based on one or more of a service type, a traffic type, WTRUcategories, and/or a WTRU capability. For example, the nominal systembandwidth for a broadband service may be located in a differentfrequency region from the frequency region for a massive MTC (mMTC)service (e.g., mMTC 1212). A WTRU may find a nominal system bandwidthwith a defined synchronization signal. The synchronization signal typemay be determined based on one or more of a service type, a traffictype, WTRU categories, and/or a WTRU capability.

A WTRU and/or a base station device may use a search space. For example,a search space may be used wherein one or more control channel (CC)candidates may be located. The number of CC candidates in a search spacemay be determined based on one or more of service types and/or traffictypes. The number of CC candidates in a search space may be determinedbased on a WTRU capability and/or category. The WTRU capability and/orcategory may include one or more of supportable uplink and/or downlinkbandwidth, number of carriers, number of transmit and/or receiveantennas, and/or receive processing time. The number of CC candidates ina search space may be determined based on a time and/or frequencyresource, and/or the number of CC candidates in a search space may bedetermined based on an associated reference signal type. The referencesignal type may be replaced by CRE type, CREG type, or RB type. A searchspace associated with a defined service type may include a smallernumber of CC candidates. A search space associated with another servicetype may include a larger number of CC candidates. A search spaceassociated with a defined service type may include CC candidates thatmay use a same type of CRE and/or CREG.

A WTRU and/or a base station device may use downlink control information(DCI) in order to implement a flexible radio access communicationsystem. The DCI may be used to schedule a downlink data and/or an uplinkdata. DCI may include one or more of a resource allocation of theassociated data channel; a modulation and coding scheme; a starting BTI;an ending BTI; a transport block size; a HARQ process number; a new dataindicator; a carrier indicator; a number of spatial layers; and/or anuplink power control field.

One or more search spaces may be configured for a WTRU in order toimplement a flexible radio access communication system. The WTRU mayreport associated channel status information for the configured searchspaces. The WTRU may report a received signal power level of a (e.g.,each) configured search space. The WTRU may report a search space whichmay have a highest receives signal power level. The WTRU may report apreferred CC candidate index within a search space. The WTRU may reportits capability of downlink control channel processing time.

Systems, methods, and instrumentalities may be disclosed forimplementing a flexible radio access communication system. A flexibleradio access communication system may be supported using spectrum ofvarying size, including aggregation of non-adjacent carriers in the sameand/or in different frequency bands. A wireless transmit/receive unit(WTRU) may receive a first transmission via a common downlink controlchannel. The first transmission may include first control information.The first control information may include information regarding theconfiguration of a first dedicated downlink control channel of one ormore dedicated control channels. The WTRU may receive a secondtransmission via the first dedicated downlink control channel of thededicated control channels. The second transmission may include secondcontrol information. The second control information may be associatedwith a transmission of a first transmission type. The dedicated downlinkcontrol channels may be used for providing control informationassociated with different types of transmissions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented.

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A.

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A.

FIG. 1D is a system diagram of another example radio access network andanother example core network that may be used within the communicationssystem illustrated in FIG. 1A.

FIG. 1E is a system diagram of another example radio access network andanother example core network that may be used within the communicationssystem illustrated in FIG. 1A.

FIG. 2 illustrates an example of transmission bandwidths that may beused by a wireless transmit/receive unit (WTRU).

FIG. 3 illustrates an example of spectrum allocation.

FIG. 4 illustrates timing relationships in an example time-divisionduplexing (TDD) frame structure.

FIG. 5 illustrates timing relationships in an example frequency-divisionduplexing (FDD) frame structure.

FIG. 6 illustrates an example of physical resource definition with aflexible system configuration.

FIG. 7 illustrates an example of multiplexing of multiple resource block(RB) types in a subframe.

FIG. 8 illustrates an example of control resource element (CRE) typesdefined or configured based on RB types.

FIG. 9 illustrates example control resource element group (CREG) types.

FIG. 10 illustrates an example hierarchical downlink control channel.

FIG. 11 illustrates an example mapping between a downlink (DL) transportchannel and a DL control channel.

FIG. 12 illustrates an example of flexible spectrum allocation.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary and in no way limitthe scope of the application.

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications system 100may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, and/or 102 d (whichgenerally or collectively may be referred to as WTRU 102), a radioaccess network (RAN) 103/104/105, a core network 106/107/109, a publicswitched telephone network (PSTN) 108, the Internet 110, and othernetworks 112, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations, networks,and/or network elements. Each of the WTRUs 102 a, 102 b, 102 c, 102 dmay be any type of device configured to operate and/or communicate in awireless environment. By way of example, the WTRUs 102 a, 102 b, 102 c,102 d may be configured to transmit and/or receive wireless signals andmay include user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, and the like.

The communications system 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106/107/109, theInternet 110, and/or the networks 112. By way of example, the basestations 114 a, 114 b may be a base transceiver station (BTS), a Node-B,an eNode B, a Home Node B, a Home eNode B, a site controller, an accesspoint (AP), a wireless router, and the like. While the base stations 114a, 114 b are each depicted as a single element, it will be appreciatedthat the base stations 114 a, 114 b may include any number ofinterconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 103/104/105, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 114 a and/or the base station114 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 114 a may be dividedinto three sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, e.g., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 115/116/117,which may be any suitable wireless communication link (e.g., radiofrequency (RF), microwave, infrared (IR), ultraviolet (UV), visiblelight, etc.). The air interface 115/116/117 may be established using anysuitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 103/104/105 and the WTRUs 102a, 102 b, 102 c may implement a radio technology such as UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA),which may establish the air interface 115/116/117 using wideband CDMA(WCDMA).

WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access(HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface115/116/117 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (e.g.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106/107/109.

The RAN 103/104/105 may be in communication with the core network106/107/109, which may be any type of network configured to providevoice, data, applications, and/or voice over internet protocol (VoIP)services to one or more of the WTRUs 102 a, 102 b, 102 c, 102 d. Forexample, the core network 106/107/109 may provide call control, billingservices, mobile location-based services, pre-paid calling, Internetconnectivity, video distribution, etc., and/or perform high-levelsecurity functions, such as user authentication. Although not shown inFIG. 1A, it will be appreciated that the RAN 103/104/105 and/or the corenetwork 106/107/109 may be in direct or indirect communication withother RANs that employ the same RAT as the RAN 103/104/105 or adifferent RAT. For example, in addition to being connected to the RAN103/104/105, which may be utilizing an E-UTRA radio technology, the corenetwork 106/107/109 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106/107/109 may also serve as a gateway for the WTRUs102 a, 102 b, 102 c, 102 d to access the PSTN 108, the Internet 110,and/or other networks 112. The PSTN 108 may include circuit-switchedtelephone networks that provide plain old telephone service (POTS). TheInternet 110 may include a global system of interconnected computernetworks and devices that use common communication protocols, such asthe transmission control protocol (TCP), user datagram protocol (UDP)and the internet protocol (IP) in the TCP/IP internet protocol suite.The networks 112 may include wired or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another core network connected to one or moreRANS, which may employ the same RAT as the RAN 103/104/105 or adifferent RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment. Also, embodiments contemplate that thebase stations 114 a and 114 b, and/or the nodes that base stations 114 aand 114 b may represent, such as but not limited to transceiver station(BTS), a Node-B, a site controller, an access point (AP), a home node-B,an evolved home node-B (eNodeB), a home evolved node-B (HeNB orHeNodeB), a home evolved node-B gateway, and proxy nodes, among others,may include some or all of the elements depicted in FIG. 1B anddescribed herein.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip. A processor, such as the processor 118, may include integratedmemory (e.g., WTRU 102 may include a chipset that includes a processorand associated memory). Memory may refer to memory that is integratedwith a processor (e.g., processor 118) or memory that is otherwiseassociated with a device (e.g., WTRU 102). The memory may benon-transitory. The memory may include (e.g., store) instructions thatmay be executed by the processor (e.g., software and/or firmwareinstructions). For example, the memory may include instructions thatwhen executed may cause the processor to implement one or more of theimplementations described herein.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 115/116/117. For example, in one embodiment,the transmit/receive element 122 may be an antenna configured totransmit and/or receive RF signals. In another embodiment, thetransmit/receive element 122 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet another embodiment, the transmit/receive element 122 may beconfigured to transmit and receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 115/116/117.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130, the removable memory 132, and/ormemory integrated with the processor 118. The non-removable memory 130may include random-access memory (RAM), read-only memory (ROM), a harddisk, or any other type of memory storage device. The removable memory132 may include a subscriber identity module (SIM) card, a memory stick,a secure digital (SD) memory card, and the like. In other embodiments,the processor 118 may access information from, and store data in, memorythat is not physically located on the WTRU 102, such as on a server or ahome computer (not shown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 115/116/117from a base station (e.g., base stations 114 a, 114 b) and/or determineits location based on the timing of the signals being received from twoor more nearby base stations. It will be appreciated that the WTRU 102may acquire location information by way of any suitablelocation-determination implementation while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 103 and the core network 106according to an embodiment. As noted above, the RAN 103 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 115. The RAN 103 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 103 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 115. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 103. TheRAN 103 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 103 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 103 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 103 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 1D is a system diagram of the RAN 104 and the core network 107according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 107.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1D, theeNode-Bs 160 a, 160 b, 160 c may communicate with one another over an X2interface.

The core network 107 shown in FIG. 1D may include a mobility managementgateway (MME) 162, a serving gateway 164, and a packet data network(PDN) gateway 166. While each of the foregoing elements are depicted aspart of the core network 107, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 162 may be connected to each of the eNode-Bs 160 a, 160 b, 160 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 164 may be connected to each of the eNode-Bs 160 a,160 b, 160 c in the RAN 104 via the S1 interface. The serving gateway164 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 164 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 164 may also be connected to the PDN gateway 166,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 107 may facilitate communications with other networks.For example, the core network 107 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 107 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 107 and the PSTN 108. In addition, the corenetwork 107 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 1E is a system diagram of the RAN 105 and the core network 109according to an embodiment. The RAN 105 may be an access service network(ASN) that employs IEEE 802.16 radio technology to communicate with theWTRUs 102 a, 102 b, 102 c over the air interface 117. As will be furtherdiscussed below, the communication links between the differentfunctional entities of the WTRUs 102 a, 102 b, 102 c, the RAN 105, andthe core network 109 may be defined as reference points.

As shown in FIG. 1E, the RAN 105 may include base stations 180 a, 180 b,180 c, and an ASN gateway 182, though it will be appreciated that theRAN 105 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 180 a, 180 b,180 c may each be associated with a particular cell (not shown) in theRAN 105 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 117. In oneembodiment, the base stations 180 a, 180 b, 180 c may implement MIMOtechnology. Thus, the base station 180 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 180 a, 180 b, 180 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 182 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 109, and the like.

The air interface 117 between the WTRUs 102 a, 102 b, 102 c and the RAN105 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, 102 cmay establish a logical interface (not shown) with the core network 109.The logical interface between the WTRUs 102 a, 102 b, 102 c and the corenetwork 109 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 180 a, 180 b,180 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 180 a, 180 b,180 c and the ASN gateway 182 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs102 a, 102 b, 102 c.

As shown in FIG. 1E, the RAN 105 may be connected to the core network109. The communication link between the RAN 105 and the core network 109may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 109 may include a mobile IP home agent(MIP-HA) 184, an authentication, authorization, accounting (AAA) server186, and a gateway 188. While each of the foregoing elements aredepicted as part of the core network 109, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 184 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 186 may be responsible for userauthentication and for supporting user services. The gateway 188 mayfacilitate interworking with other networks. For example, the gateway188 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 188 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1E, it will be appreciated that the RAN 105may be connected to other ASNs and the core network 109 may be connectedto other core networks. The communication link between the RAN 105 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 105 and the other ASNs. The communication link betweenthe core network 109 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

For emerging next generation wireless communication systems (e.g., suchas 5G systems), the air interface (e.g., the radio interface between aWTRU and one or more base station units and/or one or more other WTRUSs)may be designed to attempt to enable improved broadband (IBB)performance, support industrial control and communications (ICC)application, support vehicular applications (V2X), and/or supportmassive machine-type communications (mMTC). In order to support thesediverse application types, a flexible wireless communicationarchitecture for transmissions between different devices in the networkmay be used.

To support the flexible operation, baseband filtering offrequency-domain waveforms may be utilized by a WTRU and/or a basestation device. Baseband filtering of frequency-domain waveforms mayenable aggregation of spectrum within a given RF transceiver path. Forexample, baseband filtering of frequency-domain waveforms may enableeffective aggregation of up to 150-200 MHz total spectrum within a givenRF transceiver path. Aggregation of spectrum across operating bands(e.g., widely separated operating bands, such as 900 MHz and/or 3.5 GHz)may use multiple RF transceiver chains. For example, aggregation ofspectrum across widely separated operating bands may use multiple RFtransceiver chains due to antenna size constraints and/or amplifieroptimization design constraints. A WTRU implementation may include oneor more (e.g., three) RF transceiver paths. For example, a WTRUimplementation may include an RF transceiver for a first frequencyregion (e.g., an RF transceiver path below 1 GHz), an RF transceiverpath for a second frequency region (e.g., an RF transceiver path for the1.8-3.5 GHz frequency range), and an RF transceiver path for a thirdfrequency region (e.g., an RF transceiver path for the 4-6 GHz frequencyrange). Massive MIMO antenna configurations may be utilized by the WTRUand/or the base station device to support the flexible operation.Massive MIMO antenna configurations may be natively supported. Multiplefrequency bands with spectrum of one or more sizes (e.g., varying sizes)may be aggregated. For example, a base station device may aggregatemultiple frequency bands with spectrum of one or more sizes (e.g.,varying sizes). A base station device may aggregate multiple frequencybands with spectrum of one or more sizes to achieve data rates on theorder of several tens of Mbps at cell edges to peak data rates ofseveral Gbps. Typical data rates may be on the order of several hundredsof Mbps.

For one or more types of transmissions, a WTRU and/or a base stationdevice may utilize ultra-low transmission latency in order to implementa flexible radio access communication system. For example, air interfacelatency (e.g., as low as 1 ms round trip time (RTT)) may be utilized bythe WTRU and/or the base station device in order to implement a flexibleradio access communication system. Air interface latency (e.g., as lowas 1 ms round trip time (RTT)) may be supported by TTIs in the 100-250μs range. Ultra-low access latency (e.g., the time from the initialsystem access until the completion of the transmission of the first userdata plane unit) may be utilized by a WTRU and/or a base station devicein order to implement a flexible radio access communication system.Mobility for speeds in the range of 0-500 km/h may be utilized by theWTRU and/or the base state device. IC and/or V2X may support a packetloss rate of less than 10 e⁻⁶.

A WTRU and/or a base station device may utilize machine typecommunication (MTC) operation (such as narrowband operation) in order toimplement a flexible radio access communication system. The WTRU and/orthe base station device may utilize an air interface that may supportnarrowband operation (e.g., using less than 200 KHz), extended batterylife (e.g., up to 15 years of autonomy), and/or minimal communicationoverhead for small and/or infrequent data transmissions. For example,the WTRU and/or the base station device may utilize an air interfacethat may support a low data rate in the range of 1-100 kbps with accesslatency of seconds to hours.

A WTRU and/or a base station device may utilize narrowband operation tosupport massive MTC (mMTC) operation. A link budget may be comparable tothat of LTE extended coverage and/or the link budget may support MTCdevices (e.g., a large number of MTC devices, such as up to 200 k/km²).A link budget may be comparable to that of LTE extended coverage and/ormay support a large number of MTC devices without adversely impactingspectral efficiency for one or more supported services (e.g., one ormore other supported services).

A WTRU and/or a base station device may utilize a flexible radio accesswireless communication system that may enable flexible spectrum usage,flexible deployment strategies, and/or flexible operation. The WTRUand/or the base station device may utilize flexible operation to supportusing spectrum of varying size. For example, the WTRU and/or the basestation device may utilize flexible operation that may be supportedusing spectrum of varying size, including aggregation of non-adjacentcarriers in the same and/or in different frequency bands (e.g., licensedor unlicensed). The WTRU and/or the base station device may utilizenarrowband and/or wideband in order to implement a flexible radio accesscommunication system. The WTRU and/or the base station device mayutilize one or more (e.g., different) duplexing methods. Fortime-division duplexing (TDD), the WTRU and/or the base station devicemay utilize dynamically variable DL/UL allocation. The WTRU and/or thebase station device may utilize variable TTI lengths. The WTRU and/orthe base station device may utilize scheduled and unscheduledtransmissions. The WTRU and/or the base station device may utilizesynchronous and/or asynchronous transmissions. The user plane may beseparated from the control plane. The WTRU and/or the base stationdevice may utilize multi-node connectivity.

The wireless communication system (e.g., the flexible radio accesscommunication system) described herein may integrate with and/or operatewith legacy interfaces (or evolutions thereof). For example, thewireless communication system described herein may integrate with and/oroperate with legacy interfaces, at least toward the legacy core network(CN) (e.g., the S1 interface, NAS) and eNBs (e.g., the X2 interfaceincluding dual connectivity with LTE). The wireless communication systemdescribed herein may enable legacy aspects. For example, the wirelesscommunication system described herein may enable support for existingquality of service (QoS) and/or security mechanisms. The WTRU and/or thebase station device may utilize D2D/sidelink operation. The WTRU and/orthe base station device may utilize licensed assisted access (LAA)operation using LBT in order to implement a flexible radio accesscommunication system. The WTRU and/or the base station device mayutilize relaying.

The WTRU and/or the base station device may utilize orthogonal frequencydivision multiplexing (OFDM). OFDM may be a signal format used for datatransmissions in long term evolution (LTE) and/or IEEE 802.11communication systems. The WTRU and/or the base station device mayutilize OFDM to divide a spectrum into multiple parallel orthogonalsubbands. The WTRU and/or the base station device may shape a subcarrierusing a rectangular window in the time domain leading to sinc-shapedsubcarriers in the frequency domain. Orthogonal frequency divisionmultiplexing access (OFDMA) may benefit from frequency synchronizationand/or tight management of uplink timing alignment within the durationof the cyclic prefix. For example, OFDMA may benefit from frequencysynchronization and/or tight management of uplink timing alignmentwithin the duration of the cyclic prefix to maintain orthogonalitybetween signals and/or to reduce inter-carrier interference. Suchsynchronization may not be well-suited in a system in which a wirelesstransmit/receive unit (WTRU) is connected to multiple access pointssimultaneously. Power reduction (e.g., additional power reduction) maybe applied to uplink transmissions. For example, additional powerreduction may be applied to uplink transmissions for compliance withspectral emission guidelines to adjacent bands (e.g., in the presence ofaggregation of fragmented spectrum for the WTRU's transmissions).

More stringent RF guidelines for implementations of OFDM (e.g., CP-OFDM)may address some of the shortcomings of OFDM (e.g., CP-OFDM). Forexample, some of the shortcomings of OFDM (e.g., CP-OFDM) may beaddressed by more stringent RF guidelines for implementations whenoperating using large amounts of contiguous spectrum that may notrequire aggregation. A CP-based OFDM transmission scheme may employ adownlink physical layer that may be modified in pilot signal densityand/or location.

A WTRU and/or a base station device may utilize a downlink transmissionscheme (e.g., a scheme that may be based on a multicarrier waveform) inorder to implement a flexible radio access communication system. Themulticarrier waveform may be characterized by high spectral containment(e.g., lower side lobes and/or lower out-of-band (OOB) emissions).Waveform candidates may include OFDM-OQAM and/or UFMC (UF-OFDM).

A WTRU and/or a base station device may utilize multicarrier modulationwaveforms in order to implement a flexible radio access communicationsystem. Multicarrier modulation waveforms may divide a channel intosubchannels. Multicarrier modulation waveforms may modulate data symbolson subcarriers in the subchannels.

A WTRU and/or a base station device may apply a filter in the timedomain per subcarrier to the OFDM signal. A filter may be applied in thetime domain per subcarrier to the OFDM signal to reduce OOB. Forexample, with OFDM-OQAM, a filter may be applied in the time domain persubcarrier to the OFDM signal to reduce OOB. OFDM-OQAM may cause lowinterference to adjacent bands, may not need large guard bands, and/ormay not require a cyclic prefix. OFDM-OQAM may be a popular FBMCtechnique.

The WTRU and/or the base station device may apply a filter in the timedomain to the OFDM signal to reduce OOB emissions. For example, withUFMC (UF-OFDM), the WTRU and/or the base station device may apply afilter in the time domain to the OFDM signal to reduce OOB emissions.Filtering may be applied per subband. For example, filtering may beapplied per subband to use spectrum fragments. Complexity may bereduced. UF-OFDM may be practical to implement. UF-OFDM may improve overOFDM. For example, UF-OFDM may improve over OFDM at the edges of thefiltered spectrum.

Methods disclosed herein may be described with respect to OFDM-OQAMand/or UFMC (UF-OFDM) waveforms, but the methods described herein may beapplied to other types of waveforms in a flexible radio access wirelesscommunication system. For example, the disclosed subject matter may bedisclosed in the context of OFDM-OQAM and/or UFMC (UF-OFDM) waveformsfor purposes of illustration and not limitation.

A WTRU and/or the base station device may utilize multiple waveformsand/or different types of waveforms. By utilizing multiple waveformsand/or different types of waveforms, a WTRU and/or base station devicemay be able to perform multiplexing in frequency of signals withnon-orthogonal characteristics. Non-orthogonal characteristics mayinclude different subcarrier spacing and/or coexistence of asynchronoussignals without the use of complex interference cancellation receivers.Aggregating fragmented pieces of spectrum in the baseband processing maybe facilitated as a lower cost alternative to such aggregation as partof RF processing.

The WTRU and/or the base station device may utilize different waveformsthat may coexist within one or more bands in in order to implement aflexible radio access communication system. Different waveforms maycoexist within the same band. The WTRU and/or the base station devicemay utilize mMTC narrowband (e.g., using SCMA). The WTRU and/or the basestation device may combine different waveforms (e.g., CP-OFDM,OFDM-OQAM, and/or UF-OFDM) within the same band for one or more (e.g.,all) aspects, for downlink transmissions, and/or for uplinktransmissions.

The WTRU and/or the base station device may utilize an uplinktransmission scheme that may use a waveform. For example, the WTRUand/or the base station device may utilize an uplink transmission schemethat may use the same or different waveform as used for downlinktransmissions. Multiplexing of transmissions to and/or from WTRUs in thesame cell may be based on FDMA and/or TDMA.

The WTRU and/or the base station device may utilize spectrum flexibility(e.g., a high degree of spectrum flexibility). Spectrum flexibility(e.g., a high degree of spectrum flexibility) may enable deployment indifferent frequency bands with different characteristics. For example,spectrum flexibility (e.g., a high degree of spectrum flexibility) mayenable deployment in different frequency bands with different duplexarrangements. Spectrum flexibility (e.g., a high degree of spectrumflexibility) may enable deployment in different and/or variable sizes ofavailable spectrum, including contiguous and non-contiguous spectrumallocations in the same or different bands. The WTRU and/or the basestation device may utilize variable timing aspects. For example, theWTRU and/or the base station device may utilize variable timing aspectsfor multiple TTI lengths and/or asynchronous transmissions.

The WTRU and/or the base station device may utilize TDD and/or FDDduplexing schemes. For FDD operation, the WTRU and/or the base stationdevice may utilize supplemental downlink operation using spectrumaggregation. FDD operation may support full-duplex FDD and/orhalf-duplex FDD operation. For TDD operation, the DL/UL allocation maybe dynamic. For example, for TDD operation, the length of a downlink(DL) and/or an uplink (UL) transmission interval may be set pertransmission opportunity rather than on a fixed DL/UL frameconfiguration.

The WTRU and/or the base station device may utilize differenttransmission bandwidths on the uplink and downlink. For example, FIG. 2illustrates an example spectrum deployment for supporting a flexibleradio access wireless communication system As illustrated in FIG. 2,transmission bandwidths may range from a nominal system bandwidth 202(e.g., 5 MHz) to a maximum value. The maximum value may correspond tothe system bandwidth 204 (e.g., 20 MHz). For single carrier operations,example supported system bandwidths may include 5 MHz, 10 MHz, 20 MHz,40 MHz, and/or 80 MHz. The WTRU and/or the base station device mayutilize narrowband transmissions (e.g., up to 200 KHz) within theoperating bandwidth for MTC devices.

The WTRU and/or the base station device may utilize system bandwidth inorder to implement a flexible radio access communication system. Systembandwidth may refer to the largest portion of spectrum that may bemanaged by the network for a given carrier. For a carrier, the portionthat a WTRU supports (e.g., minimally supports) for cell acquisition,measurements, and/or initial access to the network may correspond to thenominal system bandwidth. The WTRU may be configured with a channelbandwidth that may be within the range of the system bandwidth (e.g.,the entire system bandwidth). The WTRU's configured channel bandwidthmay include the nominal part of the system bandwidth, as shown in FIG.2. For example, the WTRU's configured channel bandwidth may include aUEx Channel Bandwidth 206 (e.g., 10 MHz), a UEy Channel Bandwidth 208(e.g., 20 MHz), and/or a UEz Channel Bandwidth 210 (5 MHz).

A WTRU and/or base station device in a flexible radio access wirelesscommunication system may be configured to utilize bandwidth in aflexible and/or dynamic manner. For example, a WTRU and/or a basestation device may achieve bandwidth flexibility because RF requirementsfor an operating bandwidth (e.g., a given maximum operating bandwidth)in a band may be met without the introduction of additional allowedchannel bandwidths for that operating band. RF requirements for a givenmaximum operating bandwidth in a band may be met without theintroduction of additional allowed channel bandwidths for that operatingband due to the efficient support of baseband filtering of the frequencydomain waveform.

A WTRU and/or a base station device in a flexible radio access wirelesscommunication system may utilize a physical layer. A physical layer maybe band-agnostic and/or may support operation in licensed bands. Forexample, a physical layer may be band-agnostic and/or may supportoperation in licensed bands below 5 GHz and/or operation in theunlicensed bands in the range 5-6 GHz. For operation in the unlicensedbands, a WTRU and/or base station device may utilize an LBT Cat 4 basedchannel access framework (e.g., similar to LTE LAA).

A WTRU and/or a base station device in a flexible radio access wirelesscommunication system may utilize a frequency division multiplexing (FDM)operation. Downlink control channels and/or signals may supportfrequency division multiplexing (FDM) operation. For example, a WTRU mayacquire a downlink carrier by receiving transmissions using the nominalpart of the system bandwidth. The WTRU may not be required to receive(e.g., initially required to receive) transmissions covering the entirebandwidth that is being managed by the network for the concernedcarrier.

A WTRU and/or a base station device in a flexible radio access wirelesscommunication system may utilize downlink data channels. Downlink datachannels may be allocated over a bandwidth that may correspond to thenominal system bandwidth. For example, downlink data channels may beallocated over a bandwidth that may correspond to the nominal systembandwidth, without restrictions other than being within the WTRU'sconfigured channel bandwidth. The network may operate a carrier with asystem bandwidth (e.g., 12 MHz system bandwidth) using a nominalbandwidth (e.g., 5 MHz nominal bandwidth). Operating a carrier with a 12MHz system bandwidth, using a 5 MHz nominal bandwidth, may allow devicessupporting at most 5 MHz maximum RF bandwidth to acquire and/or accessthe system while allocating +10 to ˜10 MHz of the carrier frequency toother WTRUs supporting up to 20 MHz worth of channel bandwidth.

FIG. 3 illustrates an example of spectrum allocation. For example, FIG.3 illustrates an example of spectrum allocation utilized by a WTRUand/or a base station device over a Nominal System Bandwidth 302 (e.g.,5 MHz) and/or a System Bandwidth 304 (e.g., 20 MHz). One or moresubcarriers may be conceptually assigned to one or more modes ofoperation (e.g., SOM). For example, Sub-carrier 306 and/or Sub-carrier308 may be conceptually assigned to one or more modes of operation(e.g., spectrum operating modes (SOMs)).

One or more spectrum operating modes (SOMs) can be used to fulfill oneor more requirements for one or more transmissions. For example, a SOMmay refer to a specific type of transmission scheme and/or atransmission scheme that is used for performing a certain-type ofcommunication (e.g., a low latency communication, a high reliabilitycommunication, etc.). A SOM may be defined according to one or more of asubcarrier spacing, a transmission time interval (TTI) length, and/orone or more reliability aspects (e.g., HARQ processing aspects). A SOMmay include a secondary control channel. A SOM may be used to refer to aspecific waveform and/or may be related to a processing aspect (e.g., insupport of coexistence of different waveforms in the same carrier usingFDM and/or TDM). A SOM may be used in case coexistence of FDD operationin a TDD band is supported (e.g., in a TDM manner or similar). A firsttype of SOM may be used for accessing a first network slice and a secondtype of SOM may be used for accessing a second network slice. MultipleSOMs may be used simultaneously.

For single carrier operation, a WTRU and/or a base station device mayutilize spectrum aggregation in order to implement a flexible radioaccess communication system. A WTRU and/or a base station device maysupport transmission and/or reception of one or more transport blocksover contiguous or non-contiguous sets of physical resource blocks(PRBs) within an operating band (e.g., the same operating band). Atransport block may be mapped to one or more sets (e.g., separate sets)of PRBs.

A WTRU and/or a base station device may utilize multicarrier operation.For example, a WTRU and/or a base station device may utilizemulticarrier operation using contiguous or non-contiguous spectrumblocks within an operating band (e.g., the same operating band) and/oracross two or more operating bands. A WTRU and/or a base station devicemay utilize aggregation of spectrum blocks using modes (e.g., differentmodes, such as FDD and TDD) and using channel access methods (e.g.,different channel access methods, such as licensed and/or unlicensedband operation) below 6 GHz.

A WTRU and/or a base station device may utilize high flexibility forspectrum aggregation. High flexibility for spectrum aggregation may notinvolve the use of additional channels and/or band combinations. Forexample, high flexibility for spectrum aggregation may not involve theuse of additional channels and/or band combinations, given the use ofefficient baseband filtering in the frequency domain.

A WTRU and/or a base station device may organize downlink and/or uplinktransmissions into radio frames. The radio frames may be characterizedby one or more fixed aspects (e.g., location of downlink controlinformation) and/or one or more varying aspects (e.g., transmissiontiming, supported types of transmissions).

A WTRU and/or a base station device may utilize the basic time interval(BTI). BTI may be defined as a unit in time for defining or utilizing aSOM or transmission scheme. For example, a BTI may correspond to asymbol length such an OFDM symbol length. A BTI may be expressed interms of an integer number of one or more symbols. A symbol duration maybe a function of the subcarrier spacing applicable to the time-frequencyresource. For FDD, subcarrier spacing may differ between the uplinkcarrier frequency f_(UL) and the downlink carrier frequency f_(DL) for agiven frame.

A WTRU and/or a base station device may utilize a transmission timeinterval (TTI). A TTI may be the minimum transmission time and/or aminimum time supported by the system between transmissions (e.g.,consecutive transmissions). One or more (e.g., each) of thetransmissions may be associated with one or more (e.g., different)transport blocks (TBs) for the downlink (TTI_(DL)) and/or for the uplink(UL TRx), excluding a preamble (if applicable) and/or including controlinformation (e.g., DCI for downlink and/or UCI for uplink). A TTI may beexpressed in terms of integer number of one of more BTIs. For example, aTTI may be expressed in terms of TTI_(n)(x*BTI) 420 and/or a TTI may beexpressed in terms of TTI_(n+1)(y*BTI) 422, as shown in FIG. 4. A TTImay be expressed in terms of TTI_(DL(n)) (x*BTI) 420 and/or a TTI may beexpressed in terms of TTI_(DL(n+1))(y*BTI) 422, as shown in FIG. 4.

Supported frame durations in the flexible radio access wirelesscommunication system may enable alignment with the legacy LTE timingstructure. For example, supported frame durations may include 100 μs,125 μs (1/8 ms), 142.85 μs (1/7 ms is 2 nCP LTE OFDM symbols), and/or 1ms.

FIG. 4 illustrates timing relationships in an example TDD framestructure 400 of the flexible radio access wireless communicationsystem. FIG. 5 illustrates timing relationships in an example FDD framestructure 500 of the flexible radio access wireless communicationsystem. A WTRU and/or a base station device may utilize a frame. Theframe may start with downlink control information (DCI) (such as 402 ofFIG. 4 and/or 502 of FIG. 5). The DCI may be of a fixed time durationt_(dci) (e.g., 404 of FIG. 4 and/or 504 of FIG. 5). The time duration ofthe DCI may precede a downlink data transmission (e.g., DL TRx, such asDL TRx 406 and/or 506) for the concerned carrier frequency. Theconcerned carrier frequency may include f_(UL+DL) 408 for TDD and/orf_(DL) 508 for FDD. For TDD duplexing, a frame may include a downlinkportion (e.g., DCI and/or DL TRx) and the frame may include an uplinkportion (e.g., UL TRx, such as UL TRx 410 and/or 510). A switching gap(swg, such as swg 412) may precede the uplink portion of the frame, ifpresent. For FDD duplexing, a frame may include a downlink reference TTIand/or the frame may include one or more TTIs for the uplink. The startof an uplink TTI may be derived using an offset (t_(offset), such ast_(offset) 512) applied from the start of the downlink reference framethat may overlap with the start of the uplink frame. For TDD, a WTRUand/or a base station device may utilize a D2D/V2x/Sidelink operation inthe frame. For example, for TDD, D2D/V2x/Sidelink operation in the framemay be supported by including respective downlink control and/or forwarddirection transmission in the DCI+DL TRx portion (if a semi-staticallocation of the respective resources is used) or in the DL TRx portion(for dynamic allocation) and by including the respective reversedirection transmission in the UL TRx portion. For FDD, a WTRU and/or abase station device may utilize D2D/V2x/Sidelink operation in the UL TRxportion of the frame. For example, for FDD, D2D/V2x/Sidelink operationin the UL TRx portion of the frame may be supported by includingrespective downlink control, forward direction and reverse directiontransmissions in the UL TRx portion (dynamic allocation of therespective resources may be used).

A WTRU and/or a base station device may utilize a scheduling function inthe MAC layer. Scheduling modes that may be supported may includenetwork-based scheduling for tight scheduling (e.g., tight scheduling interms of resources, timing, and/or transmission parameters of downlinktransmissions and/or uplink transmissions). Scheduling modes that may besupported may include WTRU-based scheduling for flexibility in terms oftiming and/or transmission parameters. For network-based schedulingand/or WTRU-based scheduling, scheduling information may be valid forone or more TTIs. Network-based scheduling may enable the network tomanage radio resources (e.g., the available radio resources assigned todifferent WTRUs). For example, network-based scheduling may enable thenetwork to manage available radio resources assigned to different WTRUsto optimize the sharing of such resources. A WTRU and/or a base stationdevice may utilize dynamic scheduling. WTRU-based scheduling may enablethe WTRU to access (e.g., opportunistically access) uplink resourceswith minimal latency on a per-need basis. WTRU-based scheduling mayenable the WTRU to access uplink resources within a set of shared and/ordedicated uplink resources (e.g., dynamically or fixed uplink resources)assigned by the network.

A WTRU and/or a base station device may utilize synchronized and/orunsynchronized opportunistic transmissions. A WTRU and/or a base stationdevice may utilize contention-based transmissions and/or contention-freetransmissions. The association of data available for transmission and/oravailable resources for uplink transmissions may be supported. A WTRUand/or a base station device may utilize multiplexing of data with oneor more (e.g., different) QoS requirements within a transport block(e.g., the same transport block). For example, a WTRU and/or a basestation device may utilize multiplexing of data with one or more QoSrequirements within a transport block as long as such multiplexing doesnot introduce a negative impact to the service with the most stringentQoS requirement and/or does not introduce unnecessary waste of systemresources.

A WTRU and/or a base station device may utilize a resource element (RE).An RE may be used by the WTRU and/or the base station device as aresource unit (e.g., a minimum resource unit) in a physical resourcegrid. A WTRU and/or a base station device may define one or more of REsin a physical resource grid. An RE may be, and/or may include, one ormore of the following. An RE may be and/or may include a subcarrier of amulti-carrier waveform in a time symbol (e.g., OFDM, filtered OFDM,filter bank multi-carrier; FBMC). For example, an RE may be and/or mayinclude a time symbol if the waveform is based on a single carrier. AnRE may be and/or may include a sequence of a modulated symbol in whichmultiple sequences may be used to carry data symbols. For example, amodulated symbol may carry one or more sequences. Each sequence may beused to transmit a data symbol (e.g., QPSK, 16QAM, 64QAM). An RE may beand/or may include a resource unit that may carry a data symbol.

A waveform, multiplexing scheme, and modulation scheme may be usedinterchangeably. A time symbol of a waveform, a modulated symbol, OFDMsymbol, filtered OFDM symbol, FBMC symbol, and a time symbol may be usedinterchangeably. A data symbol, a constellation, QPSK, QAM, and offsetQAM may be used interchangeably.

A WTRU and/or a base station device may utilize one or more RE types.The WTRU and/or a base station device may determine an RE type based ona frequency space (e.g., subcarrier spacing) and/or a time length (e.g.,symbol length). The WTRU and/or a base station device may determine thefrequency space and/or time length of an RE based on the frequencylocation. As illustrated in FIG. 6, an RE in a first frequency resourcemay be defined with a frequency space _(delta)F₁ 606 and/or time length_(delta)T₁ 610. An RE in a second frequency resource may be defined witha frequency space _(delta)F₂ 608 and/or time length _(delta)T₂ 612.

A resource block (RB) may be a set of REs. A WTRU and/or a base stationdevice may use one or more RB types. For example, a resource block maybe defined as one or more (e.g., a combination of one or more) REs infrequency (N_(RE,f)) and/or a number of REs in time (N_(RE,t)). The WTRUand/or a base station device may determine the number REs in time and/orfrequency based on the RB types.

A WTRU and/or a base station device may use one or more RB types. TheWTRU and/or a base station device may associate a (e.g., each) RB typewith a transmission mode (or scheme, SOM). The WTRU and/or a basestation device may configure the transmission mode (or scheme, SOM) viaa higher layer signaling and/or a broadcast signaling. The WTRU and/or abase station device may determine the transmission mode (or scheme, SOM)based on WTRU capability. The transmission mode (or scheme, SOM) may beindicated from an associated downlink control channel. The WTRU and/or abase station device may determine the transmission mode (or scheme, SOM)based on the time/frequency location of the associated downlink controlchannel. The WTRU and/or a base station device may determine thetransmission mode (or scheme, SOM) based on a downlink control candidateindex (e.g., search space location).

A WTRU and/or a base station device may determine a time and frequencylocation. For example, the WTRU and/or a base station device maydetermine a time and frequency location based on the determined RB typethat a WTRU may receive and/or that a WTRU may need to receive (and/ormonitor, decode, measure, etc.). For example, the WTRU and/or a basestation device may determine the RB type based on a time and/orfrequency location. A WTRU may be informed of the time and/or frequencylocation of an RB type that the WTRU may need to receive. An RB mayinclude a one or more (e.g., a set of) REs. The REs in an RB (and/or anRB type) may be the same type of REs (e.g., the same frequency spacingand/or time length). An RB (and/or RB pairs) may be used as a resourceunit. For example, an RB (and/or RB pairs) may be used as a minimumresource unit, to schedule a data transmission.

A transmission mode, transmission scheme, and SOM may be usedinterchangeably.

A WTRU and/or a base station device may determine an RB type. Forexample, the WTRU and/or the base station device may determine an RBtype based on one or more of a number of REs in frequency, a number ofREs in time, and/or an RE type. The WTRU and/or a base station devicemay associate the RE type with the RB type. If a network (and/or an eNB,system, etc.) uses a type of RE, the WTRU and/or a base station devicemay determine the RB type based on a number of REs in frequency and/or anumber of REs in time. Table 1.0 illustrates an example of RB types. AnRB type may be determined based on a number of REs in time and/orfrequency, subcarrier spacing of an RE, and/or time symbol length of anRE.

One or more RB types may be defined. For example, one or more RB typesmay be defined with a time symbol (e.g., a single time symbol) with oneor more subcarriers that may be used for a traffic type (e.g., a definedtraffic type) that may use a low latency connection. One or more RBtypes may be defined with a subcarrier (e.g., a single subcarrier) withone or more time symbols that may be used for a defined traffic typethat may use narrowband transmission. One or more RB types may bedefined with one or more time symbols and one or more subcarriers thatmay be used for a traffic type (e.g., a defined traffic type) that maybe characterized by high throughput performance.

TABLE 1.0 N_(RE,f) N_(RE,t) _(delta)F_(x) _(delta)T_(y) RB type-A 120 11.5 kHz 667 μs RB type-B 12 14 15 kHz 66.7 μs RB type-C 1 80 180 kHz5.56 μs RB type-D 8 10 180 kHz 5.56 μs

A WTRU and/or a base station device may multiplex one or more RB types.For example, one or more RB types may be multiplexed in a subframe. Asubframe may be a predefined time period and/or a frequency bandwidth. Asubframe may be defined as a set of RBs. FIG. 7 illustrates an exampleof multiplexing of one or more RB types in a subframe. For example, FIG.7 illustrates an example of multiplexing RB Type-A 702, RB Type-B 704,and/or RB Type-C 706.

A WTRU and/or a base station device may determine the RB type in asubframe, based on a frequency location of the RB. The RB type in asubframe may be determined based on a time/frequency location of the RB.The RB type in a subframe may be determined based on a WTRU scheduled inthe RB. For example, a WTRU may be configured with an RB type (e.g., adetermined RB type) for data transmission/reception. The scheduled RBmay be determined as the configured RB type for the WTRU.

A WTRU and/or a base station device may define an RB as a chunk of timeand/or as frequency resources. The WTRU and/or a base station device maydetermine the number of REs for a RB, based on the subcarrier numberand/or the number of modulated symbols within the chunk of time and/orfrequency resources. The number of REs in a RB may be determined basedon a type of modulation (e.g., OFDM, FBMC, etc.).

A WTRU and/or a base station device may use one or more downlink controlchannels (and/or downlink control channel types). For example, one ormore downlink control channels (and/or downlink control channel types)may be used based on one or more of a traffic type for a data channel,an information type carried in the control channel, a reference signal,RB types used for the downlink control channel transmission, SOM, and/orWTRU types (or categories) that may receive or monitor the controlchannel. A downlink control channel may be interchangeably used as adownlink control channel type, control channel, and control channeltype.

A WTRU and/or a base station device may define (e.g., and/or determineand/or use) a downlink control channel. For example, a downlink controlchannel may be defined, determined, and/or used based on a traffic typeof the data channel scheduled by the downlink control channel. The WTRUand/or a base station device may use a first type of downlink controlchannel for a first traffic type (e.g., delay tolerant traffic). TheWTRU and/or a base station device may use a second type of downlinkcontrol channel for a second traffic type (e.g., low latency traffic).The traffic type may be a data traffic that may use a low latencyconnection. The low latency connection may be referred to as a HARQtiming (or HARQ round trip time) that may be less than a predefinedthreshold. Round trip delay may be less than a predefined threshold. Thetraffic type may be a data traffic that may use a narrowbandtransmission. The traffic type may be a data traffic that may use atransmission with a high reliability. The traffic type may be a controltraffic that may carry broadcast or multicast information. The traffictype may be a control and/or data traffic that may be transmitted and/orreceived between WTRUs.

A WTRU and/or a base station device may define (e.g., and/or determineand/or use) a downlink control channel, based on a WTRU capability. Afirst downlink control channel type may be used for a WTRU with alimited WTRU capability. A second downlink control channel type may beused for a WTRU with a full WTRU capability. The WTRU capability mayinclude a supportable bandwidth (e.g., RF and/or baseband bandwidthsupported by the WTRU). The WTRU capability may include a number ofreceive antennas (e.g., the number of RF chains or antennas at the WTRUreceiver). The WTRU capability may include a number of transmit antennas(e.g., the number of RF chains or antennas at the WTRU transmitter). TheWTRU capability may include a receiver beamforming capability. The WTRUcapability may include a multiple antenna receiver type.

A WTRU and/or a base station device may define a downlink controlchannel, based on a reference signal. For example, a first downlinkcontrol channel may be associated with a first type of reference signal(e.g., cell-specific). A second downlink control channel may beassociated with a second type of reference signal (e.g., WTRU-specific).

A WTRU and/or a base station device may define a control resourceelement (CRE). A CRE may be defined with a group of one or more REs. TheCRE may be used interchangeably with resource element group (REG) andenhanced REG (EREG).

A WTRU and/or a base station device may define (and/or determine) a CREwith a fixed number of REs. For example, a CRE may include N_(RE,C) REs.N_(RE,C) may be a nominal number or a number of available REs. N_(RE,C)may be a nominal number and the number of available REs for a CRE may beequal to or smaller than N_(RE,C). For example, if one or more REs or aCRE are reserved for a higher priority channel (e.g., reference signal,synchronization signal, broadcasting signal), the number of availableREs for a CRE may be smaller than N_(RE,C). The available RE for a CREmay be referred to as an RE, which may be used for the control channel.The configuration of a higher priority signal may be known to a WTRU.

A WTRU and/or a base station device may define a CRE with a variablenumber of REs. For example, the WTRU and/or the base station device maydetermine the number of REs per CRE, based on an RE type for the REs inthe associated CRE. A CRE that includes a first type of REs may bedefined with a first number of REs (e.g., N_(RE,C1)). A CRE thatincludes a second type of REs may be defined with a second number of REs(e.g., N_(RE,C2)). The values of N_(RE,C1) and N_(RE,C2) may bedifferent and may be preconfigured and/or predefined. The number of REsper CRE may be determined based on an RB type. For example, the numberof REs per CRE may be determined based on an RB type of an RB in whichthe CRE may be located. A CRE in a first type of RB may be defined witha first number of REs. A CRE in a second type of RB may be defined witha second number of REs. The number of REs per CRE may be determinedbased on an index of the CRE. One or more CREs may be defined for a timecycle (e.g., TTI, subframe, radio frame). The number of REs for a CREmay be defined as a function of the CRE index. The number of REs per CREmay be determined based on a number of available REs within an RB.

A WTRU and/or a base station device may use one or more CREs. A (e.g.,each) CRE used by the WTRU and/or the base station device may include amutually orthogonal set of REs.

A WTRU and/or a base station device may use one or more CRE types. TheCRE type may be determined based on a control channel type. A CRE typefor a first control channel that uses a low latency connection may bedefined and/or configured with REs located in a time symbol (e.g., inthe same time symbol). A CRE type for a second control channel that usesa narrowband transmission may be defined and/or configured with REslocated in a subcarrier (e.g., in the same subcarrier).

A WTRU and/or a base station device may determine the CRE type based onan RB type. For example, the CRE type may be determined based on an RBtype of the configured RBs for the control channel. One or more RBs maybe configured for a control channel. The configured RBs may bedetermined as a defined RB type. The WTRU and/or the base station devicemay determine the CRE type, based on the RB type determined for theconfigured RBs for the control channel.

A WTRU and/or a base station device may determine the CRE type based onan RE type. For example, the CRE type may be determined based on an REtype of REs that may be grouped to form a CRE. If a CRE is definedand/or configured with REs that may be a defined RE type, the CRE typemay be determined based on the RE type of the REs associated with theCRE.

A WTRU and/or a base station device may determine the CRE type based ona configuration. The CRE type may be configured via a higher layersignaling and/or a broadcast channel.

A WTRU and/or a base station device may determine the CRE type based ona WTRU capability and/or category. For example, if a WTRU (e.g., adefined WTRU capability and/or WTRU category) is configured to receiveand/or is intended to monitor a downlink control channel, the CRE typefor the downlink control channel may be determined based on the WTRUcapability or category.

A WTRU and/or a base station device may determine the CRE type based ona traffic type. The traffic type may include one or more of a servicetype, a higher layer signaling type, and/or a transport block type.

A WTRU and/or a base station device may determine the CRE type based ona CP length used for a waveform.

A WTRU and/or a base station device may determine the CRE type based ona subframe type. The subframe type may be defined and/or configuredbased on a traffic type served in the subframe. For example, if asubframe is used to carry a first traffic type (e.g., low-latencytraffic), the subframe type may be referred to as a first subframe type(e.g., low latency traffic subframe). The parameters for the firstsubframe type may be determined based on a configuration (e.g., aconfiguration associated with the first subframe). Parameters of eachsubframe type may be configured with the configuration associated withthe subframe. The parameters may include one or more of a subcarrierspacing, a time symbol length, a number of subcarriers, a number of timesymbols, and/or whether the subframe includes a defined broadcastsignal.

FIG. 8 illustrates an example of CRE types defined or configured basedon RB types. For example, FIG. 8 illustrates an example of CRE Type-A802, CRE Type-B 804, and/or CRE Type-C 806. CRE Type-A 802, CRE Type-B804, and/or CRE Type-C 806 may be defined or configured based on RBtypes.

A WTRU and/or a base station device may use a single CRE type. A WTRUand/or a base station device may define or predefine a CRE. For example,a fixed nominal number of REs may be used for a CRE. The fixed nominalnumber of REs may be used for a CRE regardless of the RE type, controlchannel type, and/or WTRU capability (or WTRU category). A CRE may bedefined and/or configured as an RE.

A WTRU and/or a base station device may define and/or configure acontrol resource element group (CREG). For example, a control resourceelement group (CREG) may be defined and/or configured with a group ofone or more CREs. A CREG may be used interchangeably with controlchannel element (CCE) and/or enhanced CCE (ECCE). CREs with a same typemay be grouped to form a CREG. A CREG type may be determined based onthe CRE type. CREs may be grouped to form a CREG. For example, CREs maybe grouped to form a CREG based on a CREG type.

A WTRU and/or a base station device may define and/or use one or moreCREG types. The CREG type for a downlink control information (DCI)transmission and/or a downlink control channel may be determined basedon a channel type (e.g., the associated channel type). For example, aCREG type used for a first channel type may be different from a CREGtype used for a second channel type. A first CREG type (e.g., CREGType-A 902) may be used to carry, transmit, receive, and/or monitor aDCI associated with a first channel type (e.g., low-latency channel). Asecond CREG type (e.g., CREG Type-B 904) may be used to carry, transmit,receive, and/or monitor a DCI associated with a second channel type(e.g., a narrowband transmission). A third CREG type (e.g., CREG Type-C906) may be used to carry, transmit, receive, and/or monitor a DCIassociated with a third channel type (e.g., broadband high throughputchannel).

A WTRU and/or a base station device may determine a CREG type for adownlink control channel, based on a transmission mode. For example, aCREG type for a downlink control channel may be determined based on atransmission mode configured for a WTRU.

A WTRU and/or a base station device may define, determine, and/orconfigure a CREG type, based on time and frequency locations. Forexample, a CREG type may be defined, determined, and/or configured basedon the time and frequency locations of the CREs that are grouped to formthe CREG. FIG. 9 illustrates example CREG types. A CREG type may bedefined and/or configured with CREs that may be located in the same timesymbol and/or that may be defined in adjacent time symbols. For example,a CREG type (e.g., CREG Type-A) may use a low-latency transmission. Adownlink control channel transmission in one or more CREGs transmittedin a smaller number of time symbols may reduce the transmission delay.

A WTRU and/or a base station device may define and/or configure a CREGtype with CREs that may be located in a same set of frequency (e.g.,same set of subcarriers). For example, a CREG type (e.g., CREG Type-B)may use a downlink control channel transmission within a narrowbandwidth. A downlink control channel transmission in one or more CREGstransmitted in a smaller number of subcarriers may support narrowbandtransmission.

A WTRU and/or a base station device may define, determine, and/orconfigure a CREG, based on a set of REs. For example, a WTRU and/or abase station device may use a predetermined set of REs in one or moreRBs. The set of REs for a CREG may be defined and/or determined based onthe CREG index. A set of REs for a CREG that may be used for a firsttype of control channel may be located in a same time symbol and/or inadjacent time symbols. A set of REs for a CREG that may be used for asecond type of control channel may be located in a same frequency. A setof REs for a CREG that may be used for a second type of control channelmay be located in a same set of subcarriers and/or adjacent subcarriers.A set of REs for a CREG that may be used for a third type of controlchannel may be located in multiple RBs. The multiple RBs may be a sametype of RB.

A WTRU and/or a base station device may use a reference signal todemodulate a CRE and/or a CREG. One or more reference signal structuresmay be used for a downlink control channel. A first reference signalstructure may be a cell-specific reference signal. A cell-specificreference signal may be used for one or more downlink channels. Forexample, a reference signal may be used for a downlink control channeland/or a broadcast channel. A cell-specific reference signal may betransmitted over a system bandwidth. A cell-specific reference signalmay be used for a downlink measurement (e.g., reference signal receivedpower). A second reference signal structure may be a dedicated referencesignal. A dedicated reference signal may be used for a specific downlinkchannel. For example, a dedicated reference signal may be used for adownlink control channel. A dedicated reference signal may be used for adata channel. A dedicated reference signal may be transmitted in alocalized resource. A dedicated reference signal may be located within aresource that may be allocated, received, and/or decoded by a WTRU.

A WTRU and/or a base station device may use, define, and/or determineone or more reference signal types. For example, a reference signal typemay be used, defined, and/or determined based on time and/or frequencylocations of the reference signals (e.g., reference signal pattern in atime and frequency resource grid), a scrambling sequence, a number ofantenna ports, and/or an antenna port number.

A WTRU and/or a base station device may determine a reference signaltype for demodulating (and/or associated with) a CRE and/or a CREG. Forexample, a reference signal type for demodulating (and/or associatedwith) a CRE and/or a CREG may be determined as a function of CRE and/orCREG index. NT types of reference signals may be used. A referencesignal type may be determined as a function of a CRE index and/or a CREGindex. A modulo operation may be used to determine the reference signaltype. A predefined mapping rule may be used to determine the referencesignal type.

A WTRU and/or a base station device may determine a reference signaltype associated with a CRE and/or a CREG based on a CRE type and/or aCREG type. For example, a first reference signal type may be used for afirst CRE type (and/or CREG type). A second reference signal type may beused for a second CRE type (and/or CREG type).

A WTRU and/or a base station device may use a hierarchical downlinkcontrol channel structure. The WTRU and/or a base station device may usea common downlink control channel and/or one or more dedicated downlinkcontrol channels. The common DL control channel may be transmitted toand/or received by one or more WTRUs (e.g., all WTRUs), regardless ofservice type, traffic type, transmission type, WTRU category, and/orWTRU capabilities. The dedicated DL control channel may be transmittedto and/or received by a WTRU with a defined service type, traffic type,transmission type, WTRU category, and/or WTRU capability. A common DLcontrol channel may be used interchangeably with a root DL controlchannel and a cell-specific control channel. A dedicated DL controlchannel may be used interchangeably with service type specific DLcontrol channel, transmission type specific DL control channel, andWTRU-specific control channel.

As shown in FIG. 10, two or more layers may be used by a WTRU and/orbase station device to define a hierarchical DL control channelstructure. For example, a physical common downlink control channel(PCDCCH) may be used as a common DL control channel. A physicaldedicated downlink control channel (PDDCCH) may be used as a dedicatedDL control channel.

A WTRU may receive and/or monitor one or more DL control channels ineach layer. For example, a WTRU may need to receive and/or monitor oneor more DL control channels in each layer in case multiple layers areused in a hierarchical DL control channel structure. A WTRU may receiveand/or monitor PCDCCH 1008 in the first layer, as shown in FIG. 10. Thefirst layer may be a common DL control channel, such as the Physicalcommon DL control channel 1002. The WTRU may receive and/or monitor aPDDCCH Type (e.g., a PDDCCH Type-B 1012) in a second layer. The secondlayer may be a dedicated DL control channel, such as the Physicaldedicated DL control channel 1004. The WTRU may receive and/or monitor aPDDCCH Cat (e.g., a PDDCCH Cat-A 1010) in a third layer. The third layermay be a profile, such as the L1 profile 1006. The L1 profile 1006 mayinclude a service type and/or a PHY-QoS.

A WTRU and/or a base station device may configure a dedicated DL controlchannel (e.g., Physical dedicated DL control channel 1004) via abroadcast channel that may be scheduled from a common DL control channel(e.g., Physical common DL control channel 1002). PCDCCH 1008 may be usedto schedule a data channel which may carry a broadcasting information.The broadcasting information may include the configuration of thededicated DL control channel. A dedicated DL control channel may beconfigured via a WTRU-specific higher layer signaling.

A WTRU and/or a base station device may define a dedicated DL controlchannel (e.g., each dedicated DL control channel, such as each Physicaldedicated DL control channel 1004), with one or more properties. One ormore properties for dedicated DL control channels may be differentaccording to the dedicated DL control type. These properties may includea waveform, numerologies (e.g., subcarrier spacing, time symbol length,and/or guard time or cyclic prefix length), an RE type (and/or RB type),a CRE type (and/or CREG type), a number of RBs used, a duty cycle, anassociated reference signal, and/or a control channel type.

A WTRU and/or a base station device may use a common DL control channel(e.g., Physical common DL control channel 1002) to configure one or morededicated control channels. A dedicated control channel for a WTRU toreceive and/or monitor may be determined based on a WTRU capabilityand/or category. A dedicated control channel for a WTRU to receiveand/or monitor may be determined based on a service type and/or traffictype. A dedicated control channel for a WTRU to receive and/or monitormay be determined based on a higher layer configuration (e.g.,WTRU-specific higher layer signaling). A dedicated control channel for aWTRU to receive and/or monitor may be determined based on an indication.A dedicated control channel for a WTRU to receive and/or monitor may bedetermined based on an indication from the common DL control. A WTRUand/or a base station device may use group downlink control informationto indicate which dedicated control channel is to be received and/ormonitored (e.g., needs to be received and/or monitored) for the WTRUsreceiving and/or monitoring the group downlink control information. AWTRU and/or a base station device may determine a dedicated controlchannel for a WTRU to receive and/or monitor based on a downlinktransport channel type. For example, as illustrated in FIG. 11, one ormore downlink transport channel types (e.g., DL-SCH Type-1 1006, DL-SCHType-2 1008, and/or DL-SCH Type-x 1010) may be defined. Downlinktransport channel types may be defined within a layer (such as theDownlink Transport channel 1102 layer). One or more of the downlinktransport channel types may be associated with one or more dedicated DLcontrol channel types (e.g., PDDCCH Type-A 1112, PDDCCH Type-B 1114,and/or PDDCCH Type-X 1116). Dedicated DL control channel types may bedefined within a layer (such as the Downlink Physical channel 1104layer).

A WTRU and/or a base station device may use a single common downlinkcontrol channel to support all service types, WTRU categories, WTRUcapabilities, and/or L1 profiles.

A nominal system bandwidth (such as the Nominal System Bandwidth 1202,as depicted in FIG. 12) may be smaller or narrower than a total systembandwidth (such as Total System Bandwidth 1204). For example, a nominalsystem bandwidth may have a bandwidth of 5 MHz, and/or a total systembandwidth may have a bandwidth of 20 MHz. A nominal system bandwidththat may be smaller or narrower than a total system bandwidth may bedefined or used as a cell for cell selection or re-selection in anetwork. One or more cells may be used. A WTRU may determine one of thecells. A nominal system bandwidth may be defined or used for initialcell access. For example, if a WTRU determines a cell, the WTRU mayreceive one or more downlink signals in the nominal system bandwidth.The one or more downlink signals may include broadcast information thatmay be used to access the cell, higher layer signaling (e.g.,WTRU-specific) for a RRC connection, a reference signal or referencesignals for measurement and/or synchronization, and/or a synchronizationsignal for time and/or frequency synchronization. A WTRU and/or a basestation device may define and/or use a nominal system bandwidth forreception or monitoring of a common DL control channel.

A WTRU and/or a base station device may define a nominal systembandwidth with a subset of the total system bandwidth. A WTRU and/or abase station device may use a frequency band other than the nominalsystem bandwidth based on configurations indicated or received from thenominal system bandwidth. A common DL control channel may be transmittedfrom a base state device (e.g., an eNB) and/or received by a WTRU in anominal system bandwidth (e.g., the Nominal System Bandwidth 1202). AWTRU and/or a base station device may configure a dedicated DL controlchannel in a frequency band within a total system bandwidth (e.g., theTotal System bandwidth 1204). For example, a dedicated DL controlchannel for a control channel type (e.g., Type-A control channel) may belocated in a frequency band (e.g., RBs) used and/or configured for thetraffic type associated with the control channel type. A dedicated DLcontrol channel for a traffic type (e.g., ultra-low latency) may belocated in the frequency band assigned and/or used for the traffic type.One or more dedicated DL control channels may be located in a differentfrequency band that may be associated with the traffic type. Atime/frequency location of a dedicated DL control channel may bepredefined within a frequency band that may be configured for a traffictype and/or a service type. For example, if a WTRU receives a resourceconfiguration for a traffic type and/or a service type the WTRU may needto receive, the time/frequency location of the dedicated DL controlchannel that may be associated with the traffic type and/or service typemay be known to the WTRU.

A WTRU and/or a base station device may locate a nominal systembandwidth in a different frequency region (e.g., a set of RBs or a setof consecutive RBs). The WTRU and/or a base station device may locate anominal system bandwidth in a different frequency region, based on oneor more of a service type, a traffic type, WTRU categories, and/or aWTRU capability. For example, the nominal system bandwidth for abroadband service may be located in a different frequency region fromthe frequency region for a massive MTC (mMTC) service (e.g., mMTC 1212).A WTRU may find a nominal system bandwidth with a definedsynchronization signal. For example, a WTRU and/or a base station devicemay use one or more synchronization signal types. The synchronizationsignal type to receive may be determined based on one or more of aservice type, a traffic type, WTRU categories, and/or a WTRU capability.The nominal system bandwidth (e.g., number of RBs) may be different. Forexample, the nominal system bandwidth (e.g., number of RBs) may bedifferent based on one or more of a service type, a traffic type, WTRUcategories, and/or a WTRU capability.

A WTRU and/or a base station device may use an indication of a dedicatedDL control channel configuration. For example, a WTRU and/or a basestation device may use an explicit or implicit indication of a dedicatedDL control channel configuration. The explicit or implicit indication ofthe dedicated DL control channel configuration may be dynamic. Forexample, in the nominal system bandwidth, a DCI transmitted in a commonDL control channel may indicate the presence of a defined dedicated DLcontrol channel in the same time period (and/or the same subframe,adjacent times, and/or adjacent subframes). Based on the indication, aWTRU that receives and/or monitors a traffic type that is associatedwith the defined dedicated DL control channel may monitor and/or receivethe dedicated DL control channel indicated from the DCI.

A WTRU and/or a base station device may use a DCI that may use a groupRNTI and/or dedicated RNTI. For example, a DCI that may use a group RNTIand/or a dedicated RNTI may be used to indicate the presence of adefined dedicated DL control channel.

The DCI may include an identifier for the WTRU. For example, the DCI mayinclude an identifier for the WTRU that may be different (e.g., shorter)than the RNTI that may be used to decode on the common DL controlchannel. The identifier may be included in the DCI payload of thededicated DL control channel and/or may be used to mask a cyclicredundancy check (CRC) of the dedicated DL control channel, if present.The identifier may be, or may include, an index to a specific resourcefor the dedicated DL control channel.

A WTRU and/or a base station device may use a DCI for one or morededicated DL control channels. For example, if multiple dedicated DLcontrol channels are used, a WTRU and/or a base station device may use aseparate DCI for each dedicated DL control channel. A (e.g., each)dedicated DL control channel may be indicated from a group RNTI (e.g., adistinct group RNTI). A DCI (e.g., a same DCI) may be used for one ormore (e.g., all) dedicated DL control channels. For example, a bit fieldin a DCI may indicate which dedicated DL control channel presence isindicated. One or more WTRUs (e.g., all WTRUs) may monitor a DCI (e.g.,the same DCI) in a common DL control channel. For example, one or moreWTRUs may monitor the same DCI in a common DL control channel to receivean indication of a dedicated DL control channel.

A WTRU and/or a base station device may use a reference signal type(and/or structure or sequence) to indicate the presence of a dedicatedDL control channel. The WTRU and/or a base station device may transmit areference signal and/or a sequence in a predefined (e.g., known)location. For example, the reference signal and/or a sequence may betransmitted in the predefined location if a defined dedicated DL controlchannel is transmitted. Otherwise, the WTRU and/or a base station devicemay use the predefined or known location for the reference signal and/ora sequence for other downlink signal transmission.

A WTRU and/or a base station device may use a subframe number, radioframe number, and/or other parameters to determine the presence of adefined dedicated DL channel. The presence of a dedicated DL controlchannel may imply that a WTRU may attempt to decode, monitor, or receivethe dedicated DL control channel. For example, the presence of adedicated DL control channel may imply that a WTRU associated with thededicated DL control channel may attempt to decode, monitor, or receivethe dedicated DL control channel.

A WTRU and/or a base station device may use a DL control channelcandidate. The DL control channel candidate may be used interchangeablywith control channel (CC) candidate, CC decoding candidate, CCmonitoring candidate, and CC candidate. A CC candidate may be definedand/or configured as one or more CREGs. A CC candidate may carry a DCI.A CC candidate type may be defined or configured based on CRE typeand/or CREG type used.

A WTRU and/or a base station device may use a search space. For example,a search space may be used wherein one or more CC candidates may belocated. The number of CC candidates in a search space may be determinedbased on one or more of service types and/or traffic types. The servicetypes and/or traffic types may include ultra-low latency 1208,ultra-reliable 1210, narrowband, and broadband 1206 high throughputservices. The number of CC candidates in a search space may bedetermined based on a WTRU capability and/or category. The WTRUcapability and/or category may include one or more of supportable uplinkand/or downlink bandwidth, number of carriers, number of transmit and/orreceive antennas, and/or receive processing time. The number of CCcandidates in a search space may be determined based on a time and/orfrequency resource. The time and/or frequency resource may be configuredfor a control channel in which the search space is located. For example,a configuration with a larger frequency resource (e.g., RBs) may have alarger CC candidate as compared with that of a configuration with asmaller frequency resource. A WTRU and/or a base station device maydetermine the number of CC candidates in a search space based on anassociated reference signal type. For example, a search space associatedwith a first reference signal type may have a smaller number of CCcandidates as compared with a search space associated with a secondreference signal type. The reference signal type herein may be replacedby CRE type, CREG type, or RB type.

A search space associated with a defined service type (e.g., ultra-lowlatency) may include a smaller number of CC candidates (e.g., a singleCC candidate). A search space associated with another service type(e.g., narrowband service) may include a larger number of CC candidates(e.g., fifty CC candidates). A search space associated with a definedservice type may include CC candidates that may use a same type of CREand/or CREG.

A WTRU may attempt to decode, monitor, and/or receive one or more (e.g.,all) CC candidates in a search space. For example, a WTRU may attempt todecode, monitor, and/or receive one or more (e.g., all) CC candidates ina search space that may be associated with and/or configured to theWTRU. A WTRU may attempt to decode, monitor, and/or receive a subset ofCC candidates in a search space that may be associated with and/orconfigured to the WTRU based on one or more of a service type (and/or atraffic type), a WTRU capability (and/or a WTRU category), and/or anassociated reference signal type.

A search space may be defined and/or used for a subset of downlinkcontrol channels and/or dedicated DL control channels. For example, thesearch space may be configured and/or used for a subset of channeltypes. The search space may be configured and/or used for a subset ofCRE and/or CREG types. For example, the search space may be used forCREG type-B and type-C. The search space may be used for CREG type-B andtype-C, while no search space may be used for CREG type-A.

One or more search spaces may be configured and/or used for a WTRU. A(e.g., each) search space may be associated with a defined service typeand/or traffic type. A search space for a common DL control channel andone or more dedicated DL control channels may be configured and/or usedfor a WTRU. The search space for a common DL control channel (e.g.,common search space) may be located in a nominal system bandwidth. Thesearch spaces for one or more dedicated DL control channels (e.g.,dedicated search spaces) may be located in a frequency band. Forexample, the search spaces for one or more dedicated DL control channels(e.g., dedicated search spaces) may be located in the associatedfrequency band of a (e.g., each) dedicated DL control channel. A WTRUmay monitor and/or may attempt to decode a common search space in asubset of subframes (and/or radio frame, time frame, etc.). A WTRU maymonitor and/or attempt to decode a dedicated search space in a subset ofsubframes (and/or radio frame, time frame, etc.). The dedicated searchspace may be configured. For example, the dedicated search space may bedynamically configured. An indication may be used for the presence ofthe dedicated search space.

A search space for a common DL control channel may be used. For example,a search space for a common DL control channel may be used for aspecific service type, traffic type, WTRU category, and/or WTRUcapability. One or more search spaces for a dedicated DL control channelmay be used. For example, one or more search spaces for a dedicated DLcontrol channel may be used for a specific service type, traffic type,WTRU category, and/or WTRU capability.

A WTRU and/or a base station device may configure one or more searchspaces. A WTRU may monitor and/or attempt to decode configured searchspaces. A (e.g., each) search space may include one or more CCcandidates. The number of search spaces may change over time. Forexample, the number of search spaces may be determined based on asubframe number and/or radio frame number. The number of search spacesmay be configured via higher layer signaling.

WTRU and/or a base station device may determine the number of CCcandidates for a search space based on a number of search spaces. Forexample, the number of CC candidates for a search space may bedetermined based on the number of search spaces that a WTRU may monitorand/or attempt to decode in a same subframe and/or in a same timeperiod. The number of CC candidates may be the same for search spacesconfigured. For example, N_(CC,1) CC candidates may be in a (e.g., each)search space when N_(S,1) search spaces are configured and/or used.N_(CC,2) CC candidates may be in a (e.g., each) search space whenN_(S,2) search spaces are configured and/or used. N_(CC,1) may begreater than N_(CC,2). N_(S,1) may be greater than N_(S,2). The numberof CC candidates may be determined (e.g., independently determined) persearch space. The WTRU and/or a base station device may change thenumber of CC candidates for a search space as a function of the numberof search spaces a WTRU may monitor and/or attempt to decode in a sametime period. The number of CC candidate for a common search space may bethe same regardless of the number of search spaces. The number of CCcandidates for a dedicated search space may be determined based on thenumber of search spaces in a time period.

A WTRU and/or a base station device may configure a maximum number ofsearch spaces. The WTRU and/or a base station device may configure amaximum number of search spaces simultaneously and/or in a same timeperiod. For example, the maximum number of search spaces that may beconfigured (e.g., configured simultaneously and/or in a same timeperiod) may be determined based on one or more of a WTRU category, aWTRU capability, a service type, a traffic type, a transmission type,and/or a subframe type. For example, one or more (e.g., two) searchspaces may be the maximum number of search spaces for a MTC WTRUcategory. A WTRU and/or a base station device may use a single searchspace for narrowband service. A WTRU that may be capable of narrowbandoperation may support a single search space in a time period. Adifferent search space may be multiplexed in time.

A WTRU and/or a base station device may configure one or more searchspaces. A WTRU may monitor and/or attempt to decode a subset ofconfigured search spaces. The subset of search spaces a WTRU may monitorand/or attempt to decode may be determined based on one or more of aWTRU category, a WTRU capability, a service type, a traffic type, atransmission type, and/or a subframe type. The subset may be determinedbased on a predefined priority rule of search space type. The searchspace type may be referred to as a search space in which informationrelated a defined channel type may be transmitted.

A WTRU may receive one or more DCIs. For example, a WTRU may receive oneor more DCIs associated with downlink transmission in one or more searchspaces. A WTRU may receive one DCI for a service type and another DCIfor another service type.

Control information may be carried in a time/frequency resource used fordata transmission. One or more search spaces may be configured to aWTRU. The WTRU may monitor and/or attempt to decode a selected (and/ordetermined) subset of search spaces. The control information that may betransmitted in a non-selected (and/or non-determined) search space maybe transmitted (and/or piggybacked) in a data channel associated with acontrol channel transmitted in a selected (and/or determined) searchspace. A DCI transmitted in the selected (and/or determined) searchspace may indicate the presence of piggybacked control information. ADCI transmitted in the selected (and/or determined) search space mayindicate the time/frequency location of a data channel that may carrythe piggybacked control information. The piggybacked control informationmay be transmitted as a DCI in the selected (and/or determined) searchspace. A different RNTI may be used for a DCI in the selected searchspace and a DCI carrying piggybacked control information. A number of CCcandidates may be increased if a WTRU monitors the DCI carryingpiggybacked control information. Control information associated with aselected (and/or determined) search space and the piggybacked controlinformation may be coded (e.g., jointly coded) and/or transmitted in aDCI.

A WTRU and/or a base station device may concatenate a DCI to one or morecode blocks. For example, a DCI may be concatenated to one or more codeblocks at the beginning or at the end of the code block. The DCI may beconcatenated to one or more code blocks at the beginning or at the endof the code block of the transmission and/or to one or more transportblocks. The indication may be encoded (e.g., jointly encoded) with,and/or separately encoded from, the data in a (e.g., each) code blockand/or transport block. The indication may be used to mask the cyclicredundancy check appended at the end of a (e.g., each) code block and/ortransport block.

A WTRU and/or a base station device may use one or more code blocks withone or more associated DCI. A first DCI may be associated with a firstcode block. The first DCI may be transmitted in a control region (e.g.,a DL control channel). A second DCI may be associated with a second codeblock. The second DCI may be transmitted in the data channel (or codeblock) that may be scheduled by the first DCI. A (e.g., each) code blockmay carry data information and/or a transport block. Each code block maycarry a part of a transport block. A single HARQ-ACK may be transmittedfor a transport block. One or more code blocks may be associated with atransport block. A (e.g., each) code block may include a CRC value. Thefirst DCI that may be transmitted in a control region may include DCIfields, which may be a superset of the DCI fields of a subsequent DCI.

One or more DCIs may include a WTRU identity. For example, the first DCImay include a WTRU identity. One or more DCIs may not include a WTRUidentity. For example, subsequent DCIs may not include the WTRUidentity. The frequency resource of code blocks may be determined and/orscheduled by a first DCI. A subsequent DCI may include and/or indicateone or more of a presence of a subsequent code block, a payload size ofa subsequent code block, and/or a time resource of a subsequent codeblock.

A WTRU and/or a base station device may use downlink control informationmay to schedule a downlink data and/or an uplink data. DCI may includeone or more of a resource allocation of the associated data channel; amodulation and coding scheme; a starting BTI; an ending BTI; a transportblock size; a HARQ process number; a new data indicator; a carrierindicator; a number of spatial layers; and/or an uplink power controlfield.

A WTRU and/or a base station device may use a CRC for a DCI. The CRCsize may be determined based on the payload size of the DCI. Forexample, if a DCI payload size is smaller than a predefined threshold, afirst CRC size (e.g., 8 bits) may be used. If a DCI payload size islarger than a predefined threshold, a second CRC size (e.g., 16 bits)may be used. A CRC may be used for a DCI if the payload size of the DCIis larger than a predefined threshold.

The size of CRC may be determined based on one or more of WTRU category,WTRU capability, service type, traffic type, transmission type, and/orsubframe type. The CRC size may include a value of 0, which may beconsidered as no CRC. A CRC size of 0 may be used for a defined servicetype which may use a low latency connection (e.g., ultra-low latencyservice). A CRC size of 0 may be used for a DCI in a defined searchspace that may include a single CC candidate. A large CRC size may beused for a defined service type which may be characterized by highreliability (e.g., ultra-reliable transmission).

A WTRU and/or a base station device may use an indication (e.g., a startindication, a stop indication, etc.) to start and/or stop repetitivetransmission of a data channel. For example, a transmission mode and/orscheme may use transmission (e.g., repetitive transmission) of uplinkand/or downlink data transmission. An associated DCI may include anindication of start and/or stop of repetitive transmission. If a WTRUreceives the indication of start and/or stop of repetitive transmission,the WTRU may start and/or stop transmitting and/or receiving repetitivesignal transmissions. For example, if the WTRU receives an indication tostart, the WTRU may start transmitting and/or receiving repetitivesignal transmissions until the WTRU receives an indication to stop. Astart and stop indication may be used for a DCI associated with adefined service type (e.g., ultra-reliable service).

One or more search spaces may be configured for a WTRU in order toimplement a flexible radio access communication system. The WTRU mayreport associated channel status information for the configured searchspaces. A WTRU may report a received signal power level of a (e.g.,each) configured search space. A WTRU may report a search space whichmay have a highest receives signal power level. For example, a WTRU mayreport a preferred search space, which may have a highest receivessignal power level. A WTRU may report a preferred CC candidate indexwithin a search space.

A WTRU may report its capability of downlink control channel processingtime in order to implement a flexible radio access communication system.For example, a WTRU may report a processing time of a (e.g., each)downlink control channel type. Based on the reported processing time, atiming relationship between control channel and data channel may bedetermined. A timing relationship between control channel and HARQ-ACKmay be determined.

The processes and/or instrumentalities described herein may apply in anycombination, may apply to other wireless technologies, and for otherservices.

A WTRU may refer to an identity of the physical device, or to the user'sidentity such as subscription related identities (e.g., MSISDN, SIP URI,etc.). A WTRU may refer to application-based identities. For example, aWTRU may refer to user names that may be used per application.

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, UE, terminal, base station, RNC, and/or any host computer.

1-29. (canceled)
 30. A base station for wireless communications,comprising: a processor; and a transmitter operatively coupled to theprocessor, the transmitter configured to: transmit a first downlinkcontrol channel transmission within a first bandwidth region, whereinthe first bandwidth region is 1) a subset of a system bandwidth and 2)was used by a wireless transmit/receive unit (WTRU) when initiallyaccessing the base station; transmit configuration information relatedto: 1) a second downlink control channel transmission associated with asecond bandwidth region of the system bandwidth and 2) a set of searchspaces associated with the second bandwidth region; and transmit thesecond downlink control channel transmission within the second bandwidthregion.
 31. The base station of claim 30, wherein the configurationinformation related to the second downlink control channel transmissionis associated with any of: a waveform, a numerology, a resource elementtype, a resource block type, or a control channel type.
 32. The basestation of claim 31, wherein the numerology comprises any of: asubcarrier spacing, a time symbol length, or a cyclic prefix.
 33. Thebase station of claim 30, wherein the transmitter is further configuredto transmit an indication in the first downlink control channeltransmission.
 34. The base station of claim 30, wherein each of thefirst and second bandwidth regions is associated with a respective setof contiguous physical resource blocks.
 35. The base station of claim30, wherein the first downlink control channel transmission is a commoncontrol channel transmission, and the second downlink control channeltransmission is a dedicated control channel transmission.
 36. The basestation of claim 30, wherein the configuration information indicates atime and frequency location of the second downlink control channeltransmission associated with the second bandwidth region.
 37. The basestation of claim 30, wherein the first and second bandwidth regions areeach associated with a different numerology.
 38. The base station ofclaim 30, wherein the configuration information is transmitted usingRadio Resource Control (RRC) signaling.
 39. The base station of claim30, wherein the configuration information indicates a first set ofsearch spaces associated with the first bandwidth region is differentfrom a second set of search spaces associated with the second bandwidthregion.
 40. The base station of claim 30, wherein the configurationinformation indicates any of: a first subcarrier spacing associated withthe first bandwidth region is different from a second subcarrier spacingassociated with the second bandwidth region, or a first cyclic prefixassociated with the first bandwidth region is different from a secondcyclic prefix associated with the second bandwidth region.
 41. A methodimplemented by a base station for wireless communications, the methodcomprising: transmitting a first downlink control channel transmissionwithin a first bandwidth region, wherein the first bandwidth regionis 1) a subset of a system bandwidth and 2) was used by a wirelesstransmit/receive unit (WTRU) when initially accessing the base station;transmitting configuration information related to: 1) a second downlinkcontrol channel transmission associated with a second bandwidth regionof the system bandwidth and 2) a set of search spaces associated withthe second bandwidth region; and transmitting the second downlinkcontrol channel transmission within the second bandwidth region.
 42. Themethod of claim 41, wherein the configuration information related to thesecond downlink control channel transmission is associated with any of:a waveform, a numerology, a resource element type, a resource blocktype, or a control channel type.
 43. The method of claim 42, wherein thenumerology comprises any of: a subcarrier spacing, a time symbol length,or a cyclic prefix.
 44. The method of claim 41, wherein each of thefirst and second bandwidth regions is associated with a respective setof contiguous physical resource blocks.
 45. The method of claim 41,wherein the first downlink control channel transmission is a commoncontrol channel transmission, and the second downlink control channeltransmission is a dedicated control channel transmission.
 46. The methodof claim 41, wherein the configuration information indicates a time andfrequency location of the second downlink control channel transmissionassociated with the second bandwidth region.
 47. The method of claim 41,wherein the first and second bandwidth regions are each associated witha different numerology.
 48. The method of claim 41, wherein theconfiguration information is transmitted using Radio Resource Control(RRC) signaling.
 49. The method of claim 41, wherein the configurationinformation indicates any of: a first set of search spaces associatedwith the first bandwidth region is different from a second set of searchspaces associated with the second bandwidth region, a first subcarrierspacing associated with the first bandwidth region is different from asecond subcarrier spacing associated with the second bandwidth region,or a first cyclic prefix associated with the first bandwidth region isdifferent from a second cyclic prefix associated with the secondbandwidth region.